When a registration response from cloudflared gets lost on it's way back to the edge, the edge service will retry and send another registration request. Since cloudflared already has bound the local UDP socket for the provided request id, we want to re-send the registration response.
There are three types of retries that the edge will send:
1. A retry from the same QUIC connection index; cloudflared will just respond back with a registration response and reset the idle timer for the session.
2. A retry from a different QUIC connection index; cloudflared will need to migrate the current session connection to this new QUIC connection and reset the idle timer for the session.
3. A retry to a different cloudflared connector; cloudflared will eventually time the session out since no further packets will arrive to the session at the original connector.
Closes TUN-8709
The datagram muxer will wrap a QUIC Connection datagram read-writer operations to unmarshal datagrams from the connection to the origin with the session manager. Incoming datagram session registration operations will create new UDP sockets for sessions to proxy UDP packets between the edge and the origin. The muxer is also responsible for marshalling UDP packets and operations into datagrams for communication over the QUIC connection towards the edge.
Closes TUN-8700
New session manager leverages similar functionality that was previously
provided with datagram v2, with the distinct difference that the sessions
are registered via QUIC Datagrams and unregistered via timeouts only; the
sessions will no longer attempt to unregister sessions remotely with the
edge service.
The Session Manager is shared across all QUIC connections that cloudflared
uses to connect to the edge (typically 4). This will help cloudflared be
able to monitor all sessions across the connections and help correlate
in the future if sessions migrate across connections.
The UDP payload size is still limited to 1280 bytes across all OS's. Any
UDP packet that provides a payload size of greater than 1280 will cause
cloudflared to report (as it currently does) a log error and drop the packet.
Closes TUN-8667
Devin Carr